小飞蓬入侵对伊犁河谷草原土壤养分及活性有机碳组分的影响

Effects of Conyza canadensis invasion on soil nutrients and active organic carbon components in Yili River Valley grassland

因小飞蓬繁殖能力强,传播速度快,其入侵后排挤本土植物以较快的速度形成重度入侵群落,对草原生态系统的种类组成和群落结构产生影响.本文以伊犁河谷托乎拉苏草原内自然分布的猪毛蒿和糙叶矢车菊土著植物群落、混有少量小飞蓬的猪毛蒿和糙叶矢车菊轻度入侵群落、猪毛蒿糙叶矢车菊和小飞蓬中度入侵群落、小飞蓬重度入侵群落的4个群落为研究对象,采用样地实验的方法,研究小飞蓬入侵对土壤氮、磷、钾无机养分和活性有机碳组分变化的影响.研究表明,小飞蓬入侵后提高了土壤有机质含量.轻度入侵群落对土壤无机养分需求较大,明显降低土壤速效氮、速效磷、速效钾、硝态氮、铵态氮含量;随着入侵程度加深,逐渐恢复且均高于土著群落含量,其中速效氮含量增加不明显,重度入侵群落在0—10 cm、10—20 cm土层仍处于降低趋势.小飞蓬的入侵对于土壤活性有机碳组分影响较大.轻度入侵时降低土壤微生物活性、阻碍易氧化有机碳的积累,可溶性有机碳含量上升;小飞蓬重度入侵时对微生物量碳、易氧化有机碳含量的影响降低,并促进土壤微生物活性.

Because of its strong reproduction ability and fast propagation,the invading Conyza canadensis can push out the native plants and form a severe invasive community rapidly,which alters the species composition and community structure of the grassland ecosystem.In order to investigate the effects of Conyza canadensis invasion on soil nitrogen,phosphorus and potassium contents,as well as the content of effective and active organic carbon components using the method of field sample experiment,four communities of different invasion grades naturally distributed in Tohurasu grassland in Yili River Valley,namely the indigenous plant community of Artemisia scoparia mixed with Centaurea adpressa,lightly invasive community of a small amount of Conyza Canadensis,moderately invasive community with more of Conyza Canadensis and heavily invasive community,were chosen as the study object.The results showed that the content of soil organic matter increased after Conyza canadensis invasion.Minor invasion community had a greater demand for soil inorganic nutrients.The contents of available nitrogen,phosphorus and potassium in soil were significantly reduced.With the deepening of invasion degree,the contents of inorganic nutrients in soil recovered gradually and were higher than those in indigenous community.The increase of rapidly available nitrogen content was not obviously.The soil layer of 0—10 cm and 10—20 cm in the severe invasive community was still in a decreasing trend.The soil active organic carbon(SOC)components were significantly affected by the Conyza canadensis invasion,in the case of slight invasion,soil microbial activity was reduced,hindered the accumulation of easily oxidized organic carbon and increased the soluble organic carbon content.In the case of severe invasion,the influence on microbial biomass carbon and easily oxidized organic carbon content was reduced and soil microbial activity was promoted.